Integral reflector tubular lamp



Oct. 12, 1965 HQLCOMB 3,211,938

INTEGRAL REFLECTOR TUBULAR LAMP Filed 001;. 22, 1962 lnven tor: Richard H. Holcomb b WK 8 His A t ineg United States Patent 3,211,938 INTEGRAL REFLECTOR TUBULAR LAM? Richard H. Holcomb, South Euclid, Qhio, assignor to General Electric Company, a corporation of New York Filed Get. 22, 1962, Ser. No. 232,015 6 Claims. (Cl. 313-113) This invention relates generally to electric incandescent lamps, and more particularly to tubular doubleended lamps comprising an elongated tubular envelope having an incandescible filament extending axially thereof.

There are on the market electric lamps comprising a slender tubular quartz envelope having an elongated coiled filament extending therethrough and connected at its ends to lead-in conductors sealed through pinch seals at the end of the envelope, the filament bein supported in the envelope axis by support members of sheet metal or of wire engaging the filament and, in turn, engageable with the inner wall of the envelope. Infrared or heat lamps of this type are disclosed and claimed in U.S. Patent 2,864,025, Foote et al., and lighting lamps of this type embodying a gas filling including iodine vapor are disclosed and claimed in U.S. Patent 2,883,571, Fridrich et al.

In some applications such lamps are used in conjunction with elongated reflectors where it is desired to concentrate the energy radiated from the lamp in a given direction. It would be desirable to incorporate the reflector as an integral element of the lamp in some applications where an external reflector is not feasible. Accordingly, attempts have been made to place a reflecting surface on the outside of the lamp envelope. Since the envelope becomes heated to a high temperature, such as 500 C. for example, during operation of the lamp, the reflector material must be exceptionally resistant to oxidation. However, the metals that have good reflecting properties and are suitable for use in an ambient of air, such as gold, platinum or rhodium, adhere poorly to the quartz envelope or are easily abraded. On the other hand, a metallic reflector cannot readily be incorporated inside the conventional lamp structure because it would short circuit the filament through the support members.

Accordingly, it is an object of the invention to provide a novel structure which permits incorporating the reflector within the lamp. It is a further object to provide a lamp structure wherein the internal reflector and the filament supporting members are effectively maintained out of electrical contact with one another.

Briefly stated, the above objects are attained in ac cordance with the invention by employing an envelope of double walled tubing with the reflector located between the walls. The inner wall thereby serves as an electrical insulating layer between the metal reflector and the filament supports. For a lamp containing a reactive atmosphere, such as iodine, the space between the walls is sealed out of communication with the space within the inner wall which contains the filament.

Further features and advantages of the invention will appear from the following detailed description and from the drawing wherein:

FIG. 1 is a side view, partly in section, of a lamp embodying the invention;

FIG. 2 is a transverse cross section of the lamp in FIG. 1;

FIGS. 3 and 4 are views corresponding to FIGS. 1 and 2 respectively, of a modification; and

FIGS. 5 and 6 are views corresponding to FIGS. 1 and 2 respectively, of another modification.

Referring to FIGS. 1 and 2 of the drawing, the lamp illustrated therein comprises an envelope consisting of 3,211,933 Patented Oct. 12, 1965 coextensive outer and inner quartz tubes 1 and 2 having their opposite ends closed by respective pinch seals 3 through which extend respective lead-in conductors 4 having intermediate thin foil portions 5 hermetically sealed in the seal 3. An incandescible helically coiled tungsten wire filament 6 extends longitudinally of the inner tube 2 and is connected at its ends to the inner ends of the respective lead wires 4. The filament 6 is supported at a number of points along its length by suitable support members 7 which may consist of wire spirals engageable with the inner surface of tube 2, or of sheet metal waters or discs of the type disclosed and claimed in U.S. Patent 2,813,993, Fridrich. The inner tube 2 contains a gas filling which may consist of an inert gas such as argon in the case of an infrared lamp, and which may also include iodine vapor in the case of a lighting lamp.

The tubes 1 and 2 may be concentrically arranged. However, for easier fabrication of the lamp, the tubes 1 and 2 are preferably arranged eccentrically so that they touch along a line of tangency where they are fused together as shown most clearly in FIG. 2. The diameters of the tubes 1 and 2 are preferably chosen such as to snugly accommodate a metal reflector 8. The reflector 8 may be made of any suitable metal such as gold, silver, copper, nickel, molybdenum, etc. The space between the tubes 1 and 2 may be filled with inert gas such as argon.

In FIGS. 3 and 4 parts corresponding to those in FIGS. 1 and 2 are identified by the same reference numerals with the addition of the letter a. In this case the inner tube 2a is of shorter length than the outer tube 1a so that the seals 3a are formed from the material of the outer tube 1a only. As in FIGS. 1 and 2, the inner tube 2a is joined to the outer tube In along a line of tangency, and the filament 6a is supported within the tube 2a by support members 7:: and is connected at its ends to the inner ends of the lead-in wires 4a which have their thin foil portions 5a hermetically sealed in the pinch seals 3a. Although the reflector 8a may be made of sheet metal, it is here illustrated as composed of a curved base member of glass having a vapor deposited coating of reflecting material 9, such as aluminum or silver, on its inner or concave surface. If needed, longitudinal displacement of the reflector 8a may be prevented by stop means such as inwardly protruding indentations 10 in the outer tube 1a.

In FIGS. 5 and 6 parts corresponding to those in FIGS. 1 and 2 are identified by the same reference numerals with the addition of the letter b. In this case the outer envelope 1!: is of shorter length than the inner envelope 2b and is hermetically sealed at its ends to the outer surface of the inner tube 2b. The pinch seals 3b are formed from the material of the inner tube 2b which contains the filament 6b and supports 7b and lead-in conductors 4b extending through and hermetically sealed in the pinch seals 3b. The sheet metal reflector 3b is located in the space between the concentric tubes 1b and 2b, and the said space may be evacuated or filled with a suitable gas.

What I claim as new and desire ot Patent of the United States is:

1. An electric incandescent lamp comprising an elongated tubular double walled quartz envelope having inner and outer quartz walls, a filament extending longitudinally within the interior of the inner envelope wall, support means engaging said filament and engageable with the inner surface of said inner envelope wall for supporting the filament from said inner wall, seal portions closing opposite ends of said envelope and sealing the filament therewithin, lead-in conductors extendsecure by Letters ing through respective said seal portions and electrically connected to opposite ends of said filament, and a metal reflector in the space between said inner and outer envelope walls.

2. An electric incandescent lamp comprising an elongated tubular double walled quartz envelope including an outer quartz tube and an inner quartz tube eccentrically disposed and joined together longitudinally along a line of tangency, a filament extending longitudinally within the interior of the inner tube, support means engaging said filament and engageable with the inner surface of said inner tube for supporting the filament from said inner surface, seal :portions closing opposite ends of at least the outer tube and sealing the filament and inner tube therewithin, lead-in conductors extending through respective said seal portions and electrically connected to opposite ends of said filament, and a metal reflector in the space between said inner and outer tubes.

3. An electric incandescent lamp comprising an elongated .tubular double walled quartz envelope including an outer quartz tube and an inner quartz tube, a filament extending longitudinally within the interior of the inner tube, support means engaging said filament and engageable with the inner surface of said inner tube for supporting the filament from said inner surface, seal portions closing opposite ends of the inner tube and sealing the filament therewithin, lead-in conductors extending through respective said seal portions and electrically connected to opposite ends of said filament, said outer tube hermetically sealed at its ends to said inner tube, and a metal reflector in the space between said inner and outer tubes.

4. An electric incandescent lamp comprising an elongated tubular double walled quartz envelope including coextensive outer and inner quartz tubes, a filament extending longitudinally within the interior of the inner tube, support means engaging said filament and engageable with the inner surface of said inner tube for supporting the filament from said inner surface, seal portions closing opposite ends of both the outer and inner 4 tubes hermetically sealing the space between said tubes and sealing the filament within the inner tube, lead-in conductors extending through respective said seal portions and electrically connected to opposite ends of said filament, and a metal reflector in the space between said inner and outer tubes.

5. An electric incandescent lamp comprising an elongated tubular double Walled quartz envelope including an outer quartz tube and an inner quartz tube eccentrically disposed and joined together longitudinally along a line of tangency, said outer tube extending beyond said inner tube at both ends, a filament extending longitudinally within the interior of the inner tube, support means engaging said filament and engageable with the inner surface of said inner tube for supporting the filament from said inner surface, seal portions closing opposite ends of the outer tube and sealing the inner tube and the filament therewithin, lead-in conductors extending through respective said seal portions into the interior of respective ends of said inner tube and electrically connected to opposite ends of said filament, and a metal reflector in the space between said inner and outer tubes.

6. An electric incandescent lamp comprising an elongated .tubular double-walled quartz envelope including an outer quartz tube and an inner quartz tube eccentrically disposed and fused together longitudinally along a line of tangency, a filament extending longitudinally within the interior of the inner tube, seal portions closing opposite ends of the inner tube and sealing the filament therewithin, lead-in conductors extending through respective said seal portions and electrically connected to opposite ends of said filament, said outer tube sealed at its ends to said inner tube, and a metal reflector in the space between said inner and outer tubes.

References Cited by the Examiner UNITED STATES PATENTS 2,854,600 9/58 Van De Weijer et al. 313-413 X FOREIGN PATENTS 606,830 10/60 Canada. 83 8,796 5/52 Germany.

GEORGE N. WESTBY, Primary Examiner. 

1. AN ELECTRIC INCANDESCENT LAMP COMPRISING AN ELONGATED TUBULAR DOUBLE WALLED QUARTZ ENVELOPE HAVING INNER AND OUTER QUARTZ WALLS, A FILAMENT EXTENDING LONGITUDINALLY WITHIN THE INTERIOR OF THE INNER ENVELOPE WALL, SUPPORT MEANS ENGAGING SAID FILAMENT AND ENGAGEABLE WITH THE INNER SURFACE OF SAID INNER ENVELOPE WALL FOR SUPPORTING THE FILAMENT FROM SAID INNER WALL, SEAL PORTIONS CLOSING OPPOSIDE ENDS OF SAID ENVELOPE AND SEALING THE FILAMENT THEREWITHIN, LEAD-IN CONDUCTORS EXTENDING THROUGH RESPECTIVE SAID SEAL PRTIONS AND ELECTRICALLY CONNECTED TO OPPOSITE ENDS OF SAID FILAMENT, AND A METAL REFLECTOR IN THE SPACE BETWEEN SAID INNER AND OUTER ENVELOPE WALLS. 